1. Field of the Invention
The present invention relates to a liquid jet recording head arranged in a liquid jet recorder which discharges recording liquid (ink) as flying droplets to record characters on a record medium, and more particularly to a liquid jet recording head which discharges liquid by action of thermal energy and the substrate used for the above head.
2. Related Background Art
Generally, a recording head of a liquid jet recorder which uses the above jetting method, as shown in FIG. 8, comprises an orifice 105 for discharging the liquid, a liquid discharge unit having a liquid flow path 265 which includes a thermal action unit for applying thermal energy to the liquid for discharging the liquid, and electro-thermal transducer 103 for generating the thermal energy. For example, such recording head is disclosed in U.S. Pat. No. 4,602,261. The electro-thermal transducer comprises a pair of electrodes and a heat generating resistive layer having a heat generation area, connected to the electrodes. The thermal energy generated by the electro-thermal transducer acts on the liquids to generate air bubbles which cause rapid state change due to volume expansion and contraction.
The volume of the air bubbles correlates to the droplet diameter. Accordingly, in order to attain high quality printing and uniform printing, it is required that constants of the heat generation resistive layers corresponding to each orifice of the recording head are uniform.
The heat generation resistive layer is formed into a described shape by an etching process. In the etching process, etching solution is circulated more efficiently in the opposite end areas of the heat generating resistors than in the center area (edge effect of etching) and the etching proceeds more rapidly in the end areas. As a result, the resistive layer is narrowed widthwise.
FIG. 1 shows a distribution of the width of the heat generation resistive layer in the prior art recording head. It is seen that the width of the heat generation resistive layer at the end areas is smaller than that in the center area. As a result, in the prior art recording head, the recording density is not uniform in the direction of arrangement of the heat generation resistive layers, and the print density is lower as it goes toward the opposite ends from the center.